It is generally known that high-voltage components, such as power transformers, are subject to an ageing process which can affect electrical insulation, for example. Tests, on the power transformers, for example, are therefore worthwhile at specific time intervals to ensure correct operation of an electrical power distribution system with such high-voltage components. A test such as this is also required after the repair or servicing of a transformer. Tests such as these provide an indication of the state, for example, of the insulation and also allow the detection of other faults in the relevant high-voltage component.
High-voltage components such as power transformers are very heavy, and may even be more than 100 tonnes, depending on the electrical rating. Because of the high transport cost for the respective power transformer, it is unfeasible to transport a power transformer of this weight which has been installed within an electrical power distribution system, to a fixed-installed test panel in which it could be tested by means of an AC voltage test. Furthermore, there would need to be sufficient redundancy in a power distribution system to allow a power transformer to be removed without adversely affecting the system operation.
For this reason, such AC voltage tests of power transformers are generally carried out in situ. The test arrangement with the AC voltage generator and additional components which are required for the test, such as high-voltage inductors, voltage dividers, and measurement and evaluation apparatuses, are transported in a plurality of assemblies to the site where the power transformer to be tested is located, and is assembled there to form a test arrangement. The high-voltage inductor which is required to form a resonant circuit with the unit under test, for a resonant test, can represent a test component with a considerable size, because it has a height, for example, of 2.5 m and an internal diameter of, for example, 1 m. The voltage divider which is required to measure the high voltages of, for example, up to several 100 kV in the resonant circuit is also a component with a similar height.
When carrying out an AC voltage test, care must be taken to ensure that the components of the test arrangement are sufficiently far apart from one another, and are sufficiently far away from the adjacent ground potential, because of the high voltages which occur.
One disadvantage is that the assembly of the various assemblies on site involves a considerable amount of time. In particular, the positioning and assembly of a high-voltage inductor or of a voltage divider are highly time consuming.
Against this background, exemplary embodiments of the present disclosure provide a test arrangement which occupies less space and which can be transported in a reduced number of assemblies.